1. Field
A hermetic compressor is disclosed herein.
2. Background
In general, a hermetic compressor may include, within an inner space thereof, a motor that generates a driving force, and a compression device that compresses a refrigerant by receiving the driving force from the motor. Hermetic compressors may be classified as a single-stage hermetic compressor or a multi-stage hermetic compressor according to a number of cylinders. The single-stage hermetic compressor includes one suction pipe coupled to one cylinder, whereas the multi-stage hermetic compressor includes a plurality of suction pipes coupled to a plurality of cylinders, respectively.
The multi-stage hermetic compressor may be divided into a 1-suction and 2-discharge type and a 1-suction and 1-discharge type according to a method of compressing a refrigerant. The 1-suction and 2-discharge type (or 2-suction and 2-discharge type) is a compressor having a plurality of cylinders connected to one suction pipe in a diverging manner or connected to a plurality of suction pipes, respectively, such that each of the plurality of cylinders compresses a refrigerant and discharges the compressed refrigerant into an inner space of a hermetic casing. On the other hand, the 1-suction and 1-discharge type is a compressor having a first cylinder of a plurality of cylinders connected to a primary suction channel, and a second cylinder connected to a discharge side of the first cylinder through a secondary suction channel, such that a refrigerant is compressed by two stages to be discharged from the second cylinder into an inner space of a hermetic casing. The 1-suction and 1-discharge type may be referred to as a two-stage compression type hermetic compressor.
FIG. 1 is a longitudinal sectional view of a two-stage compression type hermetic compressor according to the related art. As illustrated in FIG. 1, in the related art two-stage compression type hermetic compressor 1, a first compression chamber S1 of a first cylinder 2 and a second compression chamber S2 of a second cylinder 3 may be independently installed in a hermetic casing 10. An inlet of the first cylinder 2 may be connected to a suction pipe 4, and an outlet of the second cylinder 3 may communicate with the hermetic casing 10.
An intermediate chamber 5, which has a predetermined inner space S3 to temporarily receive a first-stage compressed refrigerant, may be formed below the first cylinder 2. The intermediate chamber 5 may be connected to the second compression chamber S2 of the second cylinder 3 through a secondary suction channel 6, which may serve as an inner communication path.
Unexplained reference numeral 7 denotes a drive motor, and 8 denotes an accumulator in FIG. 1.
With such a configuration of a two-stage compression type hermetic compressor according to the related art, a refrigerant sucked into the first cylinder 2 through the suction pipe 4 may be first-stage compressed in the first compression chamber S1 to be discharged into the intermediate chamber 5. The first-stage compressed refrigerant may then be introduced into the second compression chamber S2 of the second cylinder 3 through the secondary suction channel 6, and then two-stage or second-stage compressed in the second compression chamber S2 of the second cylinder 3. The two-stage compressed refrigerant may be discharged into the inner space of the hermetic casing 10. This series of processes may be repetitively executed.
A first pressure reduction may be caused while or when the refrigerant is sucked into the first compression chamber S1 of the first cylinder 2, and a second pressure reduction may be caused while or when the refrigerant is discharged from the first compression chamber S1 of the first cylinder 2 into the intermediate chamber 5 to be introduced into the second compression chamber S2 of the second cylinder 3 through the secondary suction channel 6. In the related art, to reduce pressure and pressure pulsation, the inner space S3 of the intermediate chamber 5 is formed as large as possible and a cross section of the secondary suction channel 6 is also large.
However, when the reduction of the pressure and the pressure pulsation is derived by increasing a volume of the intermediate chamber 5 and the cross section of the secondary suction channel 6, as shown in the related art two-stage compression type hermetic compressor, as illustrated in FIG. 2, an oil accumulation in the inner space S3 of the intermediate chamber 5 is caused due to an inlet of the secondary suction channel 6 being formed at an upper end of the intermediate chamber 5. This may cause the inner space S3 of the intermediate chamber 4 to become narrower, which may aggravate or reduce the second pressure reduction. Also, the second cylinder 3 may suffer from a frictional loss due to a relative shortage of oil.